Description:    For super high-rise buildings, the vibration period of the basic mode is several seconds, and it is very close to the period of the fluctuating wind. The damping of super high-rise buildings is low, so super high-rise buildings are very sensitive to fluctuating wind. The wind load is one of the key loads in the design of super high-rise buildings. It is known that only the basic mode is needed in the wind-response analysis of tall buildings. However, for super high-rise buildings, especially for the acceleration response, because of the frequency amplification of the high modes, the high modes and the mode coupling may need to be considered. Three typical super high-rise projects with the SMPSS in wind tunnel tests and the random vibration theory method were used to analyze the effect of high modes on the wind-induced response. The conclusions can be drawn as follows. First, for the displacement response, the basic mode is dominant, and the high modes can be neglected. Second, for the acceleration response, the high modes and the mode coupling should be considered. Lastly, the strain energy of modes can only give the vibration energy distribution of the high-rise building, and it cannot describe the local wind-induced vibration of high-rise buildings, especially for the top acceleration response. Content Type Journal Article Pages 427-434 DOI 10.1007/s11803-012-0132-2 Authors Ruoqiang Feng, The Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, Southeast University, Nanjing, 210096 China Guirong Yan, Department of Civil Engineering, University of Texas at El Paso, El Paso, Texas 79968, USA Jinming Ge, The Key Laboratory of Concrete and Prestressed Concrete Structures of Ministry of Education, Southeast University, Nanjing, 210096 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    The equivalent linearization method approximates the maximum displacement response of nonlinear structures through the corresponding equivalent linear system. By using the particle swarm optimization technique, a new statistical approach is developed to determine the key parameters of such an equivalent linear system over a 2D space of period and damping ratio. The new optimization criterion realizes the consideration of the structural safety margin in the equivalent linearization method when applied to the performance-based seismic design/evaluation of engineering structures. As an application, equations for equivalent system parameters of both bilinear hysteretic and stiffness degrading single-degree-offreedom systems are deduced with the assumption of a constant ductility ratio. Error analyses are also performed to validate the proposed approach. Content Type Journal Article Pages 415-425 DOI 10.1007/s11803-012-0131-3 Authors Liang Su, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058 China Nan Xiao, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058 China Yi Wang, China Aviation Planning and Construction Development Co., Ltd, Beijing, 100120 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    The current AASHTO load and resistance factor design (LRFD) guidelines are formulated based on bridge reliability, which interprets traditional design safety factors into more rigorously deduced factors based on the theory of probability. This is a major advancement in bridge design specifications. However, LRFD is only calibrated for dead and live loads. In cases when extreme loads are significant, they need to be individually assessed. Combining regular loads with extreme loads has been a major challenge, mainly because the extreme loads are time variables and cannot be directly combined with time invariant loads to formulate the probability of structural failure. To overcome these difficulties, this paper suggests a methodology of comprehensive reliability, by introducing the concept of partial failure probability to separate the loads so that each individual load combination under a certain condition can be approximated as time invariant. Based on these conditions, the extreme loads (also referred to as multiple hazard or MH loads) can be broken down into single effects. In Part II of this paper, a further breakdown of these conditional occurrence probabilities into pure conditions is discussed by using a live truck and earthquake loads on a bridge as an example. There are three major steps in establishing load factors from MH load distributions: (1) formulate the failure probabilities; (2) normalize various load distributions; and (3) establish design limit state equations. This paper describes the formulation of the failure probabilities of single and combined loads. Content Type Journal Article Pages 293-301 DOI 10.1007/s11803-012-0122-4 Authors Zach Liang, Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14261, USA George C. Lee, Department of Civil, Structural and Environmental Engineering, University at Buffalo, Buffalo, NY 14261, USA Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    Tuned mass dampers (TMDs) have been widely used in recent years to mitigate structural vibration. However, the damping mechanisms employed in the TMDs are mostly based on viscous dampers, which have several well-known disadvantages, such as oil leakage and difficult adjustment of damping ratio for an operating TMD. Alternatively, eddy current damping (ECD) that does not require any contact with the main structure is a potential solution. This paper discusses the design, analysis, manufacture and testing of a large-scale horizontal TMD based on ECD. First, the theoretical model of ECD is formulated, then one large-scale horizontal TMD using ECD is constructed, and finally performance tests of the TMD are conducted. The test results show that the proposed TMD has a very low intrinsic damping ratio, while the damping ratio due to ECD is the dominant damping source, which can be as large as 15% in a proper configuration. In addition, the damping ratios estimated with the theoretical model are roughly consistent with those identified from the test results, and the source of this error is investigated. Moreover, it is demonstrated that the damping ratio in the proposed TMD can be easily adjusted by varying the air gap between permanent magnets and conductive plates. In view of practical applications, possible improvements and feasibility considerations for the proposed TMD are then discussed. It is confirmed that the proposed TMD with ECD is reliable and feasible for use in structural vibration control. Content Type Journal Article Pages 391-401 DOI 10.1007/s11803-012-0129-x Authors Zhihao Wang, Wind Engineering Research Center, Hunan University, Changsha, 410082 China Zhengqing Chen, Wind Engineering Research Center, Hunan University, Changsha, 410082 China Jianhui Wang, Wind Engineering Research Center, Hunan University, Changsha, 410082 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    In this study, through novel drift-based equations of motion in the frequency domain, optimum placement and characteristics of linear velocity-dependent dampers are investigated. In this study, the sum of the square of the absolute values of transfer matrix elements for interstory drifts is considered as the optimization index. Optimum placement and characteristics of dampers are simultaneously obtained by minimizing the optimization index through an incremental procedure. In each step of the procedure, a predefined value is considered as the damper characteristic. The optimum story for this increment is selected such that it leads to a minimum value for the optimization index. The procedure is repeated for the next increments until the optimization index meets its target value, which is obtained according to the desired damping ratio for the overall structure. In other words, the desired overall damping ratio is the input to the proposed procedure, and the optimal placement and characteristics of the dampers are its output. It is observed that the optimal placement of a velocitydependent damper depends on the damping coefficient of the added damper, frequency of the excitation, and distribution of the mass, stiffness, and inherent damping of the main structure. Content Type Journal Article Pages 403-414 DOI 10.1007/s11803-012-0130-4 Authors Seyed Amin Mousavi, R&D Department, Sabok Sazan Sarie Engineering Company, Tehran, Iran Amir K. Ghorbani-Tanha, School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    This paper evaluates different characteristics for earthquake early warning. The scaling relationships between magnitude, epicenter distance and calculated parameters are derived from earthquake event data from USGS. The standard STA/LTA method is modified by adding two new parameters to eliminate the effects of the spike-type noise and small pulsetype noise ahead of the onset of the P-wave. After the detection of the P-wave, the algorithm extracts 12 kinds of parameters from the first 3 seconds of the P-wave. Then stepwise regression analysis of these parameters is performed to estimate the epicentral distance and magnitude. Six different parameters are selected to estimate the epicentral distance, and the median error for all 419 estimates is 16.5 km. Four parameters are optimally combined to estimate the magnitude, and the mean error for all events is 0.0 magnitude units, with a standard deviation of 0.5. Finally, based on the estimation results, additional work is proposed to improve the accuracy of the results. Content Type Journal Article Pages 435-443 DOI 10.1007/s11803-012-0133-1 Authors Qingkai Kong, Building Engineering Department, Tongji University, Shanghai, 200092 China Ming Zhao, Building Engineering Department, Tongji University, Shanghai, 200092 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    This paper examines the quasi-static cyclic behavior, lateral strength and equivalent damping capacities of a system of post-tensioned segmental bridge columns tied with large diameter martensitic Shape Memory Alloy (SMA) link-bars. Moment-curvature constitutive relationships are formulated and analysis tools are developed for the PT column, including a modified four-spring model prepared for the SMA bars. The suggested system is exemplified using a column with an aspect ratio of 7.5 and twelve 36.5 mm diameter NiTi martensitic SMA bars. A post-tensioning force of 40% to 60% of the tendon yield strength is applied in order to obtain a self re-centering system, considering the residual stress of the martensitic SMA bars. The cyclic response results show that the lateral strength remains consistently around 10% of the total vertical load and the equivalent viscous damping ratios reach 10%–12% of critical. When large diameter NiTi superelastic SMA bars are incorporated into the column system, the cyclic response varies substantially. The creep behavior of the superelastic SMA bar is accounted for since it affects the re-centering capability of the column. Two examples are presented to emphasize the modeling sensitivities for these special bars and quantify their cyclic behavior effects within the column assembly. Content Type Journal Article Pages 375-389 DOI 10.1007/s11803-012-0128-y Authors Hwasung Roh, Dept. of Civil and Environmental Engineering, Hanyang University, Ansan, Gyeonggi-do, 426-791 South Korea Andrei M. Reinhorn, Dept. of Civil, Structural and Environmental Engineering, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA Jong Seh Lee, Dept. of Civil and Environmental Engineering, Hanyang University, Ansan, Gyeonggi-do, 426-791 South Korea Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    In this paper, an experimental and analytical study of two half-scale steel X-braced frames with equal nominal shear strength under cyclic loading is described. In these tests, all members except the braces are similar. The braces are made of various steel grades to monitor the effects of seismic excitation. Internal stiffeners are employed to limit the local buckling and increase the fracture life of the steel bracing. A heavy central core is introduced at the intersection of the braces to decrease their effective length. Recent seismic specifications are considered in the design of the X-braced frame members to verify their efficiency. The failure modes of the X-braced frames are also illustrated. It is observed that the energy dissipation capacity, ultimate load capacity and ductility of the system increase considerably by using lower grade steel and proposed detailing. Analytical modeling of the specimens using nonlinear finite element software supports the experimental findings. Content Type Journal Article Pages 313-329 DOI 10.1007/s11803-012-0124-2 Authors Parviz Ebadi, Structural Engineering, Khaje Nasir Toosi University of Technology, Tehran, Iran Saeid Sabouri-Ghomi, Structural Engineering, Khaje Nasir Toosi University of Technology, Tehran, Iran Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete (RC) building sand studying the vulnerability of existing buildings. The Chinese Code for Seismic Design of Buildings (CCSDB) has evolved over time, however, there is still reported earthquake induced damage of newly designed RC buildings. Thus, to investigate modern Chinese seismic design code, three low-, mid- and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model (PSDM).The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center. Finally, the PSDM was used to generate fragility curves for immediate occupancy, significant damage, and collapse prevention damage levels. Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level. Content Type Journal Article Pages 331-342 DOI 10.1007/s11803-012-0125-1 Authors D. Wu, Key Laboratory of Earthquake Engineering and Applied Technique of Guangdong Province, Guangzhou, 501405 China S. Tesfamariam, School of Engineering, University of British Columbia, Kelowna, V1V 1V7 Canada S. F. Stiemer, Dept. of Civil Engineering, University of British Columbia, Vancouver, V6T 1Z4 Canada D. Qin, Dept. of Civil Engineering, Radio, Film and Television Design and Research Institute, Beijing, 100045 China Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3

Description:    The current AASHTO load and resistance factor design (LRFD) guidelines are formulated based on bridge reliability, which interprets traditional design safety factors into more rigorously deduced factors based on the theory of probability. This is a major advancement in bridge design specifications. However, LRFD is only calibrated for dead and live loads. In cases when extreme loads are significant, they need to be individually assessed. Combining regular loads with extreme loads has been a major challenge, mainly because the extreme loads are time variable and cannot be directly combined with time invariant loads to formulate the probability of structural failure. To overcome these difficulties, this paper suggests a methodology of comprehensive reliability, by introducing the concept of partial failure probability to separate the loads so that each individual load combination under a certain condition can be approximated as time invariant. Based on these conditions, the extreme loads (also referred to as multiple hazard or MH loads) can be broken down into single effects. In this paper, a further breakdown of these conditional occurrence probabilities into pure conditions is discussed by using a live truck and earthquake loads on a bridge as an example. Content Type Journal Article Pages 303-311 DOI 10.1007/s11803-012-0123-3 Authors Zach Liang, Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14261, USA George C. Lee, Department of Civil, Structural and Environmental Engineering, University at Buffalo, Buffalo, NY 14261, USA Journal Earthquake Engineering and Engineering Vibration Online ISSN 1993-503X Print ISSN 1671-3664 Journal Volume Volume 11 Journal Issue Volume 11, Number 3